If you taught her the fingerspelling of the ABC's for sign language you mean she can't pronounce the letters in English? No duh? Do you know the Spanish fingerspelled alphabet, they do have one, it has more letters than the Ameslan or Signed English alphabet.
If I remember correctly when I studied it the Spanish ABC's (abecedario) has 30 letters.
Do you know how to pronounce them all?
Why is it we expect everyone to learn English if we're not willing to become polyglots ourselves as Americans living in a continent where Spanish and French are major languages too?
BTW most of the Western part of what we call now the United States was once Spanish and Native American speaking. English came later, it's been less than 200 years since a lot of the States in the Union joined the U.S.
Before that, Spanish was spoken among Native American tribes in the South West, due to the Spanish arriving in the early 1500, and running rampage through the continent with their toledo steel swords and armor, horses and gunpowder, and let's not forget the European diseases brought into the New World. But it seems most Americans either don't pay attention in World History class enough to learn about what happened before the English came over and established the 13 colonies in the East Coast.
Ok, rant over, but I think the level of literacy in most Spanish speaking countries is quite high; Spanish is quite phonetic unlike English, and places like Cuba have a higher percent of literacy than even the U.S., go figure.